Police say the owner of the home was illegally cooking butane hash oil. And they say, they’d never seen an explosion so severe.

“It was completely blown away, all walls were down, even the foundation was blown up,” said Joseph Luiz, an detective with the Portland Police Bureau.

Luiz, along with his partner, Detective Rick McGraw of the Portland Fire Department, said the explosion in Northeast Portland killed two people, blew the home off its foundation and also destroyed neighbors’ homes and property.

“It felt like I was walking into a war zone,” said neighbor Ed Kaiel. The blast rocked his home across the ally. “The debris and the force from the blast blew in the garage door, blew it off the rails.”

Even though it happened last summer, experts say the threat a deadly hash oil explosion is just as likely today, and it could happen right next door. Luiz says more amateurs are cooking hash oil, using butane to extract the oil from the part of the marijuana plant normally thrown away. It’s a highly flammable, heavy gas that ignites with something as simple as static electricity.

“If the gas to air ratio is just right, within this range, and an ignition source is available, and that ignition source by the way can be as simple as static electricity, walking across the carpeted floor for example, could cause that thing to blow,” said Luiz. “I think it’s a huge problem, I mean the potential for destruction is just amazing.”

The potency of hash oil is almost pure, some say 90-percent pure THC. That’s nearly five times as potent as a normal joint. And, it’s in high demand. You can buy it online, and Ruiz says a lot of people are now illegally making it in some dangerous places.

“Bathroom of a gas station, in a vehicle that was parked, in a motor home, in an apartment complex, downstairs of an apartment complex… all over the place.”

Investigators say making hash oil so common because butane gas is so available. More than 400 cans were found at the explosion in Northeast Portland.

“Knowing what I know, I would be going after butane sales, and the extent of butane sales,” said McGraw.

A single 300-milliliter can of butane will refill a lighter for several years, but illegal hash oil cookers are buying it by the caseload at convenience stores and headshops all over town. KGW was able to buy a case in five minutes, no questions asked. Luiz says that’s a problem.

“There's an enormous amount of it being sold, so you can assume that an enormous amount of it is being produced somewhere in your neighborhood.”

Detective McGraw says it might be time for lawmakers to consider the abundant sales of butane. “If they could limit sales, I think that would be just like taking ephedrine away from the meth production.”

But until something is done, cooking hash oil is likely to continue. And like those who saw their neighborhood blow up, like Ed Kaiel will have a hard time knowing what is going on at the neighbor’s house. “I had no idea that somebody would be running that kind of business.”

He says the best advice may be, to keep a close eye on what’s going on. “I think people need to know who their neighbors are and pay attention.”

The Oregon Liquor Control Commission monitors the marijuana industry in Oregon. The agency says most marijuana retailers, about 530 shops, have sold hash oil, but only a few processors extract it, because it’s such an expensive investment in extraction equipment.

The OLCC does have a very extensive "seed to sale" tracking system. Compliance by the OLCC has traditionally been "complaint based" but the agency says the state is now headed in the direction of "proactive enforcement."